Technical Information - PSF (Pneumatic Spring Fork) Front Fork (KX450FD ∼)
This model has adopted Pneumatic Spring Fork (PSF)
system. Unlike conventional front forks, PSF does not have
a main spring in each leg and uses air pressure as a spring
[A] Air Valve Plug
2) New Features
In the conventional design, the main springs constitute about 12% of the total mass of a front fork.
Eliminating the main springs has realized a significant reduction in mass (–750 g/1.5 lb.).
Improvement of Operation
The total friction of the front fork has been reduced by about 20% due to elimination of the main
springs that mainly cause friction in the latter half of the stroke.
The balance spring within the cartridge has a slider that minimizes the friction created during stroke.
A new oil seal developed specifically for PFS's air pressurizing system for smooth initial movement.
[B] Balance Spring
[C] New Oil Seal
Improvement of "Bottoming Resistance"/Front Wheel Grip
The larger cylinder diameter ( 24→ 32) is possible due to the elimination of the main spring, which
contributes to double the pressurized area of the main piston.
The big piston contributes to increased bottoming resistance near the end of the compression stroke.
The larger cylinder and piston generates damping force quickly and can maintain it throughout the
extension stroke. The pressurized system prevents oil cavitation when the fork is near full extension
to maintain consistent and stable damping force.
Front wheel grip has been further improved due to softer spring force during the rebound stroke.
GENERAL INFORMATION 1-15